The underlying cause of all movement disorders is an error in the neuromuscular pathways, leading to an excessive stimulation of muscles. Muscles are always tense and in a state of constant contraction, whereas they should be relaxed and unflexed. Constant tension causes pain and disability.
Movement disorders occur in certain neurological diseases when different parts of the body exhibit either excessive, uncontrolled and abnormal movements, or shortage of movement. Shortage of movement in these cases is not due to paralysis or weakness of muscles. The underlying cause of movement disorders is pathology in the brain cells associated with movement. The brain cell pathology can cause hyperkinesia (excessive and involuntary muscle movement) or hypokinesia (lack of purposeful movement).
Injectable toxin is a complex protein used to provide sustained relief to patients in various movement disorders. Once injected inside the nerve cells, it acts at the junction of nerves and muscles to block the release of acetylcholine (the chemical messenger responsible for contraction of muscles). This reduces its concentration at the neuromuscular junction and thus, causes the muscles at the site of injection, to relax. This provides relief from various symptoms of dystonia and spasticity.
Common types of movement disorders that are treated with injectable toxin include cervical dystonia, blepharospasm, writer’s cramp, various tremors and tics, spasticity, facial spasm.
Dystonia is a condition in which there are involuntary and sustained muscle contractions causing abnormal postures or abnormal positioning of body parts. This causes limitation of motion, pain and disability. Blepharospasm is twitching and abnormal contraction of eyelids. In severe cases, it may cause functional blindness due to the patients’ inability to open their eyes. Writer’s cramp is a spasm of the muscles of hand and symptoms include loss of coordination, cramps, trembling and pain while performing simple daily tasks. Spasticity refers to spasm of muscles because of stroke, multiple sclerosis, brain injury and some other brain disorders. Facial spasm causes twitching and spasm of facial muscles.
Of the seven types of toxin, only type A and type B are used therapeutically. Only type A is available in Australia. It is selectively injected into specific muscles, where it causes temporary mild weakness. The amount of weakness caused can be regulated by varying the amount of toxin. Maximum effect occurs 4 to 5 weeks after the injection and the effect of injection lasts for about 3 to 5 months. Although patient starts noticing some improvement within few days.
Side effects of this therapy are generally mild and self limiting and include pain or discomfort at the site of injection. Allergic reactions comprising of rashes, wheezing and breathing trouble may also occur.
Injection therapy is a highly effective and safe treatment option for relief of symptoms and improvement of quality of life in patients of movement disorders. It is not recommended for individuals with existing neuromuscular disorders and heart conditions; or for women that are pregnant or nursing.